Marine Electronics Forum - Lowrance LCX-28C HD sensitivity issues...

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03-29-2012, 08:04 AM
I'm trying to hunt down the cause of a problem I'm getting with the sonar on my LCX-28C unit.

What is happening is that in shallow water, say under 20 feet the sonar is completely washed out, bright in one or two colors and you cant see bottom. If I turn the sensitivity down to say 33% then the bottom shows, but the norm factory setting for this should be in the 70%-80% range. Out in deeper water the problem isn't as bad, I can read bottom at normal sensitivity ranges but I'm not picking up many fish on the sonar. I don't think it's a noise issue since I was told by Lowrance that noise would show up as artifacts and lines.

Leading clues, I recently I added a stereo and washdown pump to the battery load, but even when they are off the problem persists. I would suspect that their install is a cause, but I can't pin-point it. The two recent additions were installed by a professional and he can't seem to locate any issues with the install.

I've called Lowrance support and was given a rediculous response that it probably is "cold water" upwelling. I know that is not the case, since the unit was working fine prior to the stereo and washdown install just a few days prior.

Has anyone expierenced anything like this before? Any advice is appreciated in hunting down this problem. Thanks.

03-29-2012, 09:02 AM
The timing does seem odd, but if the stereo and wash down pump are off, its unclear to me how they could create interference or the like - I could see if it happened when you fired one up. The stereo may still be drawing some power - what happens if you remove the fuse or the power leads to the stereo and/or washdown pump - ensuring they are fully off, not drawing any power of any form.

Any chance that in pulling wire wires for the new installed gear that the xducer wire to the Lowrance has gotten cut, pinched, crimped, etc.

Could be just an odd timing coincidence that something in the unit or maybe in the xducer has gone bad - any chance you could try another xducer - even it just held in the water while connected - to see if that's the culprit?

Can you put your Lowrance on another boat with an existing transducer / setup to see if you have the issue - would help to eliminate one of the sources of the issue.

Could be none of the above, but some things to check....

03-29-2012, 09:54 AM
I have seen a similar problem with a bad transducer
Horrid readings in shallow water but in deeper water the problem seemed to be not as bad.
Changed ducer..unit fine

Not saying this is your problem ...but worth looking into to help eliminate issues.

03-29-2012, 10:02 AM
There was a software issue in that series of units relating to shallow water that came up a few years ago and a fix was put into one of the updates. Probably not it but worth a look. You might just try a reset also if you haven't already done so.

Also make sure you have the right txducer selected and that the settings for it are correct. Try toggling between 50 and 200 if you have that option.

If that doesn't help, maybe borrow one ( i know, easier said than done) and hang it over the side on a stick to see what happens. That should rule out the transducer vs the head unit.

03-29-2012, 03:16 PM
Similar to eyder's comment, if you haven't chnged any other menu settings, just make sure you are viewing the higher freq/200khz instead of low freq 50khz by mistake. And that zoom is off.

03-29-2012, 03:25 PM
I had a similar problem and I had the very same unit. After a thorough inspection of the transducer I found a small crack in the forward leading edge. Replaced the ducer and the problem was fixed.

03-29-2012, 05:29 PM
I have also seen a similar problem with a LCX. Replacing the transducer fixed the problem.

03-29-2012, 07:19 PM
And if you do change transducers look into the Airmar P66 rather than an OEM unit.

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